The subject matter described herein relates generally to internal combustion engines, such as diesel engines.
Diesel engines include cylinders having combustion chambers with pistons disposed in the combustion chambers. The pistons move in the combustion chambers to rotate a shaft. The shaft may be coupled with an alternator or generator to create electric current. The electric current may be used to power one or more devices, such as traction motors of a powered rail vehicle that propel the rail vehicle.
In some known diesel engines, the pistons move within the combustion chambers based on a four-stroke cycle. During the four-stroke cycle, intake air is directed into the combustion chambers and is compressed and thereby heated to ignite diesel fuel sprayed into the combustion chamber towards the end of the compression stroke. The combustion of the diesel fuel creates a gaseous exhaust in the combustion chamber. The gaseous exhaust of the cylinders may include pollutants, such as nitrogen oxide (NOx) and soot. In order to reduce pollution emitted by the diesel engines, some known diesel engines attempt to change the composition of the intake air by recirculating parts of the exhaust gas back into the intake. These diesel engines may be referred to as exhaust gas recirculation (EGR) diesel engines.
In a certain configuration, an EGR diesel engine recirculates the gaseous exhaust from one or more dedicated cylinders to the other cylinders. For example, the gaseous exhaust from a first cylinder, such as an EGR donating cylinder, may be recirculated back to a set of different, second cylinders and form at least a part of the intake air that is received by the second cylinders and used to ignite the diesel fuel in the second cylinders.
In such an EGR donor engine, typically a fixed number of exhaust gas donating cylinders are provided. The amount of exhaust that is recirculated by the fixed number of donating cylinders may be unable to adapt to changing load demands of the engine or changing emissions limits.